U.S. patent application number 15/648390 was filed with the patent office on 2018-02-08 for shaft seize ring.
The applicant listed for this patent is SAFRAN ELECTRICAL & POWER. Invention is credited to Thomas E. Katcher.
Application Number | 20180038419 15/648390 |
Document ID | / |
Family ID | 59416801 |
Filed Date | 2018-02-08 |
United States Patent
Application |
20180038419 |
Kind Code |
A1 |
Katcher; Thomas E. |
February 8, 2018 |
SHAFT SEIZE RING
Abstract
A disconnect mechanism includes a shaft that rotationally
couples a prime mover and a driven element together. The disconnect
mechanism also includes a first bearing that rotationally supports
the shaft and a first seize ring rigidly attached to the shaft. The
first seize ring coaxially surrounds at least a portion of the
shaft. The disconnect mechanism also includes a housing that
retains the first bearing. The housing includes a first contact
member that is fixed with relation to the shaft. The first contact
member is concentrically spaced from the first seize ring during
the normal operation of the shaft and selectively contacts the
first seize ring when the centerline control of the shaft is not
maintained. The disconnect mechanism also includes a torque
activated disconnect element that rotationally decouples the prime
mover and the driven element from one another when the first seize
ring contacts the first contact member.
Inventors: |
Katcher; Thomas E.; (Euclid,
OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAFRAN ELECTRICAL & POWER |
Blagnac Cedex |
|
FR |
|
|
Family ID: |
59416801 |
Appl. No.: |
15/648390 |
Filed: |
July 12, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62371398 |
Aug 5, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16D 7/021 20130101;
F16D 9/06 20130101; F16D 2127/005 20130101; F16D 59/00
20130101 |
International
Class: |
F16D 7/02 20060101
F16D007/02; F16D 9/06 20060101 F16D009/06 |
Claims
1. A disconnect mechanism, comprising: a shaft that rotationally
couples a prime mover and a driven element together, the shaft
defining a radial centerline extending along a longitudinal axis; a
first bearing that rotationally supports the shaft so as to provide
radial centerline control of the shaft to define a normal operation
of the shaft; a first seize ring rigidly attached to the shaft, the
first seize ring coaxially surrounding at least a portion of the
shaft; a housing that retains the first bearing, the housing
including a first contact member that is fixed with relation to the
shaft, wherein the first contact member is concentrically spaced
from the first seize ring during the normal operation of the shaft
and selectively contacts the first seize ring when the centerline
control of the shaft is not maintained; and a torque activated
disconnect element that rotationally decouples the prime mover and
the driven element from one another when the first seize ring
contacts the first contact member.
2. The disconnect mechanism of claim 1, wherein the torque
activated disconnect element includes a shear neck portion defining
a shear neck diameter and a non-shear neck portion defining a
non-shear neck diameter, wherein the shear neck diameter is less
than the non-shear neck diameter.
3. The disconnect mechanism of claim 1, wherein when the centerline
control of the shaft is not maintained due to failure of the first
bearing, the first contact member contacts the first seize ring so
as to cause thermal expansion of the first seize ring thereby
resulting in an interference fit between the first contact member
and the first seize ring.
4. The disconnect mechanism of claim 1, wherein the torque
activated disconnect element includes at least one shear pin that
has a shear strength that is less than a shear strength of the
shaft.
5. The disconnect mechanism of claim 4, wherein the at least one
shear pin primarily extends in a direction that is generally
parallel to the longitudinal axis.
6. The disconnect mechanism of claim 4, wherein the at least one
shear pin primarily extends in a direction that is generally
perpendicular to the longitudinal axis.
7. The disconnect mechanism of claim 1, wherein the torque
activated disconnect element includes a clutch that rotationally
disconnects the prime mover from the driven element.
8. The disconnect mechanism of claim 1, wherein the first bearing
is disposed such that the first seize ring is longitudinally
between the first bearing and the torque activated disconnect
element.
9. The disconnect mechanism of claim 1, wherein the torque
activated disconnect element includes a clutch.
10. The disconnect mechanism of claim 1, further including a second
bearing that cooperates with the first bearing to rotationally
support the shaft, wherein the first seize ring is disposed so as
to be longitudinally between the first bearing and the second
bearing.
11. The disconnect mechanism of claim 10, further including a
second seize ring rigidly attached to the shaft and longitudinally
spaced from the first seize ring, the second seize ring coaxially
surrounding at least a portion of the shaft and being disposed
between the second bearing and the torque activated disconnect
element.
12. The disconnect mechanism of claim 11, wherein the first seize
ring defines a first seize ring outer diameter and the second seize
ring defines a second seize ring outer diameter, and wherein the
first seize ring outer diameter is equal to the second seize ring
outer diameter.
13. The disconnect mechanism of claim 1, wherein the first seize
ring is constructed of a first material and the first contact
member is constructed of a second material, and wherein the first
material has a thermal expansion coefficient that is greater than a
thermal expansion coefficient of the second material.
14. The disconnect mechanism of claim 13, wherein the first
material and the second material are adapted to gall upon contact
with one another.
15. The disconnect mechanism of claim 1, further comprising: an oil
slinger that is directly attached to the first seize ring.
16. A power distribution assembly, comprising: a prime mover that
provides rotational energy; a driven element that is powered by the
prime mover; and a disconnect mechanism that includes: a shaft that
rotationally couples the prime mover and the driven element
together, a first bearing and a second bearing that rotationally
support the shaft, a first seize ring that coaxially receives the
shaft, and a housing that rotationally supports the first bearing
and the second bearing, the housing including a first contact
member that selectively contacts the first seize ring, wherein the
first seize ring is adapted to thermally expand in an outwardly
radial manner after contact with the first contact member so as to
prevent rotation of the shaft.
17. The power distribution assembly of claim 16, wherein when
centerline control of the shaft is maintained, the first bearing
and the second bearing define a first bearing operating radial
clearance and a second bearing operating radial clearance,
respectively, and when the centerline control of the shaft is not
maintained, at least one of the first bearing and the second
bearing defines a failed bearing operating radial clearance; and
wherein the failed bearing operating radial clearance is greater
than the first bearing operating radial clearance and the second
bearing operating radial clearance.
18. The power distribution assembly of claim 17, wherein when the
centerline control of the shaft is maintained, the first contact
member is radially spaced from the shaft a distance that is greater
than the first bearing operating radial clearance and the second
bearing operating radial clearance.
19. The power distribution assembly of claim 17, wherein when the
centerline control of the shaft is not maintained, the first
contact member is radially spaced from the shaft a distance that is
less than the first bearing operating radial clearance and the
second bearing operating radial clearance.
20. The power distribution assembly of claim 16, wherein the first
contact member includes a leg that extends in a direction generally
parallel to the shaft, a main body disposed radially outward from
the first seize ring, and a blade that extends generally
perpendicular to the shaft so as to connect the leg and the main
body together, and wherein the first seize ring defines a groove
that circumferentially extends around the first seize ring so as to
receive the blade of the first contact member to define a labyrinth
seal.
Description
BACKGROUND
[0001] This disclosure relates to power distribution assemblies,
and more particularly to disconnect mechanisms which rotationally
couple a prime mover and a driven element together.
[0002] A driven element (aka driven equipment), such as electrical
generators, pumps, and compressors are rotationally connected to a
prime mover (aka power source), such as a main engine of an
aircraft. This connection can occur with a shaft, also known as a
drive shaft. While driven element is generally very reliable, it
will be appreciated that there are times when the driven element
may fail. Particularly in aircraft applications there is a need for
the driven element to fail in a safe manner. However, the prime
mover is not aware of a failure of a bearing in the driven element.
Thus, the prime mover will continue to provide power to the failed
driven element. Depending upon the failure mode, this continued
supply of power can create an unsafe condition.
[0003] Further, this failure can cause increased stress to be
placed on the prime mover. Additionally, when the driven element
fails, it is sometimes possible for the internal components of the
driven element to continue to rotate. However, this post-failure
rotation mode can be especially taxing on the prime mover. Further
still, this rotation of the internal components of the prime mover,
in the post-failure mode, can result in additional damage occurring
to the driven element. Thus, many devices and methods have been
used in order to predict when a failure of the driven element would
occur.
[0004] As is done with many aviation components, the driven element
could be changed prior to failure based upon a preventative
maintenance schedule. As will be appreciated, this schedule may not
account for the exact conditions which have been subjected to the
driven element. Thus, there is the chance that the driven element
will not be changed before it would fail. Alternatively, there is
also the chance that the driven element may be changed well before
it fails, thereby sacrificing or wasting useful remaining life of
the driven element. This results in increased maintenance costs and
downtime.
[0005] Alternatively, some systems utilize a variety of sensors
disposed within on near to the driven element. These sensors may
measure, for example, temperature and/or vibration of the driven
element or the surrounding area. Then, through a predictive model,
an estimate is made of when the driven element may fail based upon
the data obtained from the sensors. As such, the driven element can
be changed prior to the estimated failure time. However, it is very
expensive and time consuming to install these additional sensors in
an attempt to determine when the driven element may fail. Further,
these sensors and related computing equipment add additional weight
to the aircraft.
[0006] Thus, to avoid the negative issues associated with a failure
of the driven element, a user is forced to either preventatively
change the driven element based upon a maintenance schedule or rely
on expensive sensors to predict when the driven element may fail.
Further, the aforementioned methods fail to address the situation
of rapidly occurring types of bearing failure modes where the
predictive maintenance system cannot respond in time to prevent
failure of the entire assembly.
SUMMARY
[0007] In view of the foregoing, a disconnect mechanism includes a
shaft that rotationally couples a prime mover and a driven element
together. The shaft defines a radial centerline that extends along
a longitudinal axis. The disconnect mechanism also includes a first
bearing that rotationally supports the shaft so as to provide
radial centerline control of the shaft to define a normal operation
of the shaft, and a first seize ring rigidly attached to the shaft.
The first seize ring coaxially surrounds at least a portion of the
shaft. The disconnect mechanism also includes a housing that
retains the first bearing. The housing includes a first contact
member that is fixed with relation to the shaft. The first contact
member is concentrically spaced from the first seize ring during
the normal operation of the shaft and selectively contacts the
first seize ring when the centerline control of the shaft is not
maintained. The disconnect mechanism also includes a torque
activated disconnect element that rotationally decouples the prime
mover and the driven element from one another when the first seize
ring contacts the first contact member.
[0008] According to another aspect, a power distribution assembly
that includes a prime mover that provides rotational energy, a
driven element that is powered by the prime mover, and a disconnect
mechanism. The disconnect mechanism includes a shaft that
rotationally couples the prime mover and the driven element
together, a first bearing and a second bearing that rotationally
support the shaft, a first seize ring that coaxially receives the
shaft, and a housing that rotationally supports the first bearing
and the second bearing. The housing includes a first contact member
that selectively contacts the first seize ring. The first seize
ring is adapted to thermally expand in an outwardly radial manner
after contact with the first contact member so as to prevent
rotation of the shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic view of a power distribution
assembly.
[0010] FIG. 2 is a schematic view of an alternate power
distribution assembly.
[0011] FIG. 3 is a schematic view of an alternate power
distribution assembly.
[0012] FIG. 4 is a partial sectional view taken along line A-A of
FIG. 1 of a disconnect mechanism in normal operation where
centerline control is maintained.
[0013] FIG. 5 is a partial sectional view taken along line A-A of
FIG. 1 of the disconnect mechanism in which centerline control has
not been maintained.
[0014] FIG. 6 is a partial sectional view taken along line A-A of
FIG. 1 of the disconnect mechanism in which the shaft has
broken.
[0015] FIG. 7 is an elevation sectional view of an axial pin
coupling.
[0016] FIG. 8 is an elevation sectional view of a radial pin
coupling.
[0017] FIG. 9 is an elevation sectional view of an overrunning disk
clutch.
[0018] FIG. 10 is an elevation sectional view of a magnetic
particle clutch.
[0019] FIG. 11 is a schematic view of an alternate power
distribution assembly.
[0020] FIG. 12 is a schematic view of an alternate power
distribution assembly.
[0021] FIG. 13 is a schematic view of an alternate power
distribution assembly.
DETAILED DESCRIPTION
[0022] FIG. 1 depicts a schematic view of a power distribution
assembly 10. The power distribution assembly 10 includes a prime
mover 12 and driven element 14. The prime mover 12 provides
rotational energy to the driven element 14. Stated another way, the
driven element 14 is powered by the prime mover 12. The power
distribution assembly 10 includes a disconnect mechanism 16 with a
torque activated disconnect element 34. The torque activated
disconnect element 34 may be disposed within the driven element 14.
Alternatively, as shown in FIG. 2, the torque activated disconnect
element 34 may be disposed within the prime mover 12. Further
still, as shown in FIG. 3, the torque activated disconnect element
34 may be disposed so as to be external to the prime mover 12 and
the driven element 14.
[0023] The torque activated disconnect element 34 is shown in
schematic form in FIGS. 1-3. However, as will be appreciated, the
torque activated disconnect element 34 could be in the form of
numerous layouts without departing from the scope of the
disclosure. For example, the torque activated disconnect element 34
could be a shear neck portion 34' as illustrated in FIGS. 4-6.
Numerous other torque activated disconnect elements 34 will be
discussed in more detail hereinafter.
[0024] With reference to FIG. 4, the disconnect mechanism 16
includes a housing 18 with a first contact member 20 and a shaft
22. The shaft 22 is rotationally supported by at least a first
bearing 24. The shaft 22 can also be supported by a second bearing
26. Further, the shaft 22 can include a splined end 28.
Additionally, the shaft 22 includes a first seize ring 32.
[0025] While the prime mover 12 is shown schematically in FIGS.
1-3, it will be appreciated that the prime mover 12 could be any
number of elements, such as, for example an aircraft engine or
other prime mover. Further, it will also be appreciated that the
driven element 14 could also be any number of devices, including
for example, an electrical generator, pump, or compressor for an
aircraft. Nevertheless, it is envisioned that the power
distribution assembly 10 could be utilized in any number of
environments in which a prime mover and a driven element are
rotationally coupled together.
[0026] As shown, the housing 18 is disposed within the driven
element 14. However, as noted hereinbefore, the housing 18 could be
located external to the driven element 14. It will also be
appreciated that the housing 18 could be integrated within the
prime mover 12 without departing from the scope of this disclosure.
It is also noted that the first contact member 20 of the housing 18
is fixed with relation to the shaft 22.
[0027] The first contact member 20 may be of a similar longitudinal
length as the first seize ring 32. The purpose and function of the
first contact member 20 is solely for selective contact with the
first seize ring 32. This contact may occur when centerline control
of the shaft 22 is not maintained or when the first seize ring 32
increases in outer diameter due to thermal expansion. The first
contact member 20 is specially designed so as to rapidly increase
the temperature of the first seize ring 32 when contact between the
objects occurs.
[0028] Further, as the purpose of the first contact member 20 is
limited to selective contact with the first seize ring 32, the
first contact member 20 is designed to so as to not cause undue or
further damage to the power distribution assembly 10 upon contact
with the first seize ring 32. The first contact member 20 can at
least partially circumferentially surround the first seize ring 32.
The first contact member 20 may be made from any number of
materials including, for example, steel, stainless steel, and
aluminum. Further, the first contact member 20 may be made of a
material that has a rate of thermal expansion that is less than the
material of which the seize ring is made.
[0029] As noted hereinbefore, the disconnect mechanism 16 also
includes the shaft 22. The shaft 22 rotationally couples the prime
mover 12 and the driven element 14 together. The shaft
longitudinally extends between the prime mover 12 and the driven
element 14. The shaft 22 can have a generally circular
cross-section. The shaft 22 can be made from any number of
materials, including for example, steel, stainless steel, nickel
super alloys, and aluminum. The shaft 22 defines a radial
centerline that extends along a longitudinal axis (i.e., extending
in a left-right direction in FIG. 4).
[0030] The first bearing 24 rotationally supports the shaft 22 so
as to provide radial centerline control of the shaft 22 to define a
normal operation of the shaft 22, as will be described in more
detail hereinafter. The second bearing 26 can cooperate with the
first bearing 24 to rotationally support and provide centerline
control of the shaft 22. The housing 18 retains and rotationally
supports the first bearing 24 and the second bearing 26. Thus,
failure of the first bearing 24 and/or the second bearing 26 can
result in a loss of centerline control of the shaft 22.
[0031] The first bearing 24 and the second bearing 26 can be of the
same type. As illustrated, the first bearing 24 and the second
bearing 26 could be rolling-element bearings. However, it will be
appreciated that other types of bearings are possible without
departing from the scope of the disclosure. As is known, bearings
include an inner race and an outer race, with bearing element(s)
radially disposed therebetween. One of the common characteristics
of all bearing failures is a loss of centerline control.
Specifically, the clearance in the bearing increases during the
failure and the shaft will drop or orbit within the increased
clearance. This situation is shown in FIG. 5.
[0032] The shaft 22 may include the splined end 28 for connection
to the prime mover 12. As shown in FIGS. 2-4, the splined end 28 is
disposed at an end of the shaft 22 that is opposite the end near
the second bearing 26. The splined end 28 allows for the addition
of longitudinal extensions (not shown) to be attached to the shaft
22.
[0033] With attention to FIGS. 4-6 and 13, the first seize ring 32
is shown. The first seize ring 32 is rigidly attached to the shaft
22 and coaxially surrounds at least a portion of the shaft 22. In
fact, the first seize ring 32 could completely surround a radial
perimeter of the shaft 22 in a select longitudinal portion of the
shaft 22. The first seize ring 32 is disposed so as to be
longitudinally between the first bearing 24 and the second bearing
26. For reference, the shaft 22 and the first seize ring 32 can be
made of different materials.
[0034] As shown in FIG. 4, the first seize ring 32 and the first
contact member 20 have a same width in the longitudinal direction
(left to right). This same width ensures good contact between the
components when centerline control of the shaft 22 is not
maintained. Thus, the prime mover 12 and the driven element 14 can
be promptly disconnected from one another as will be described
hereinafter. Further, as is also shown in FIG. 4, the first seize
ring 32 and the first contact member 20 are radially spaced from
one another so that no contact occurs between these two elements
when centerline control of the shaft 22 is maintained.
[0035] The first seize ring 32 is constructed of a first material,
whereas the first contact member 20 is constructed of a second
material. The first material may have a thermal expansion
coefficient that is greater than a thermal expansion coefficient of
the second material. The first material, i.e., the material of
which the first seize ring 32 is made, may be aluminum, steel,
stainless steel, or brass.
[0036] Further, the first material and the second material may be
adapted to gall upon contact with one another. This galling occurs
even during selective contact between the first seize ring 32 and
the first contact member 20. Galling is a form of wear caused by
adhesion between sliding surfaces, in this case the first seize
ring 32 and the first contact member 20.
[0037] Galling is caused by a combination of friction and adhesion
between the surfaces of the first seize ring 32 and the first
contact member 20, which is then followed by slipping and tearing
of crystal structure beneath the surface. This results in some
material being stuck or even friction welded to the adjacent
surface. Thus, portions of the first seize ring 32 can be deposited
onto the first contact member 20. Alternatively, portions of the
first contact member 20 can be deposited onto the first seize ring
32. This results in a radial clearance between the first seize ring
32 and the first contact member 20 being reduced.
[0038] Further, the first seize ring 32 is adapted to thermally
expand in an outwardly radial manner after contact with the first
contact member 20. This radially outward expansion of the first
seize ring 32 results in further contact between the first seize
ring 32 and the first contact member 20 until rotation of the shaft
22 is entirely prevented.
[0039] As illustrated in FIGS. 4-6 and 13, the first seize ring 32
is disposed so as to be longitudinally between the first bearing 24
and the second bearing 26. Because of this placement of the first
seize ring 32 between the first bearing 24 and the second bearing
26, several advantages are realized. Initially, the first seize
ring 32 is able to detect failure of either the first bearing 24 or
the second bearing 26 more promptly than if the first seize ring 32
was disposed such that the first bearing 24 was longitudinally
between the second bearing 26 and the first seize ring 32 or if the
second bearing 26 was longitudinally between the first bearing 24
and the first seize ring 32. Further, as the longitudinal distance
between the first bearing 24 and the second bearing 26 has already
been set, the first seize ring 32 can be integrated into the
assembly without increasing an overall length of the shaft 22.
[0040] As noted hereinbefore, the torque activated disconnect
element 34 could be of any number of layouts, as for example shown
in FIGS. 7-10. For example, the torque activated disconnect element
34 could be an axial shear pin portion 34'' that includes at least
one axial shear pin 38, as shown in FIG. 7. The axial shear pins 38
extend primarily in a direction so as to be parallel to the
longitudinal axis defined by the shaft 22. Alternatively, the
torque activated disconnect element 34 could be a radial shear pin
portion 34''' with a radial shear pin 42, as illustrated in FIG. 8.
In this arrangement, the radial shear pin 42 primarily extends in a
direction generally perpendicular to the longitudinal axis defined
by the shaft 22. The axial shear pins 38 and the radial shear pin
42 can have a shear strength that is less than a shear strength of
the shaft 22.
[0041] Further still, the torque activated disconnect element 34
could be an overrunning disk clutch 34'''', as shown in FIG. 9. The
torque activated disconnect element 34 could alternatively be a
magnetic particle clutch 34''''', as illustrated in FIG. 10. The
overrunning disk clutch 34'''' and the magnetic particle clutch
34''''' can be configured to disconnect the prime mover 12 from the
driven element 14 when a torsion in the shaft 22 is greater than a
predetermined value. As will be appreciated, this predetermined
value would be set to a value that would prevent further damage to
either the prime mover 12 or the driven element 14.
[0042] As shown in FIGS. 4-6, the torque activated disconnect
element 34 could be a shear neck portion 34'. The shaft 22 defines
the shear neck portion 34' and a non-shear neck portion 36. The
shear neck portion 34' defines a shear neck diameter and the
non-shear neck portion 36 defines a non-shear neck diameter. The
diameter of the shear neck portion 34' is less than a diameter of
the non-shear neck portion 36. As the shear neck portion 34' and
the non-shear neck portion 36 are both part of the shaft 22, it
will be appreciated that both portions 34', 36 can be made of the
same material. The shear neck portion 34' is disposed so as to be
longitudinally between the first bearing 24 and the splined end
28.
[0043] The second bearing 26 is disposed so as to be longitudinally
between the first seize ring 32 and the torque activated disconnect
element 34. Further, the first contact member 20 of the housing 18
is concentrically spaced from the first seize ring 32 during normal
operation of the shaft 22. This concentric spacing ensures that
contact between the first contact member 20 and the first seize
ring 32 will not occur during normal operation of the power
distribution assembly 10. Normal operation is defined as when
centerline control of the shaft 22 is maintained and/or temperature
of the power distribution assembly 10 is kept to a sufficiently low
temperature for sustained operation. For reference, normal
operation of the shaft 22 is illustrated in FIG. 4.
[0044] Whenever centerline control of the shaft 22 is maintained,
the first bearing 24 and the second bearing 26 define a first
bearing operating radial clearance and a second bearing operating
radial clearance respectively. However, when the centerline control
of the shaft 22 is not maintained, at least one of the first
bearing 24 and the second bearing 26 defines a failed (or
non-normal) bearing operating radial clearance. The failed bearing
operating radial clearance is greater than the first bearing
operating radial clearance or the second bearing operating radial
clearance.
[0045] Thus, when the centerline control of the shaft 22 is
maintained, the first contact member 20 is radially spaced from the
shaft 22 a distance that is greater than the first bearing
operating radial clearance or the second bearing operating radial
clearance. However, when the centerline control of the shaft 22 is
not maintained, the first contact member 20 is radially spaced from
the shaft 22 a distance that is less than the first bearing
operating radial clearance and the second bearing operating radial
clearance.
[0046] The first seize ring 32 selectively contacts the first
contact member 20 when centerline control of the shaft 22 is not
maintained. As noted hereinbefore, this may be due to failure of
either the first bearing 24 and/or the second bearing 26. It will
be appreciated that failure of a bearing can be due to a number of
reasons. These reasons may include the loss or deformation of
individual roller bearing elements and/or breakage/deformation of
an inner or outer race of the bearing.
[0047] For reference, a loss of centerline control of the shaft 22
is shown in FIG. 5. When the first contact member 20 contacts the
first seize ring 32, thermal expansion of the first seize ring 32
occurs. This results in an interference fit between the first
contact member 20 and the first seize ring 32 as is shown in FIG.
6. As will be appreciated, an interference fit is a fastening
between two parts (in this case the first contact member 20 and the
first seize ring 32), which is achieved by friction after the parts
are pushed together, rather than by any other means of
fastening.
[0048] As such, the shaft 22 near the torque activated disconnect
element 34, e.g., the shear neck portion 34', is not rotating when
the interference fit occurs. However, rotational energy is still
being supplied by the prime mover 12. As such, the shaft 22 is
adapted to torsionally shear at the shear neck portion 34' when the
interference fit occurs, thereby rotationally disconnecting the
prime mover 12 from the driven element 14, as shown in FIG. 6.
Thus, the driven element 14 is operated a minimum amount of time
post-failure. In fact, it is entirely possible that rotation of the
shaft 22, and hence internal operating components (not shown) of
the driven element 14 is ceased before the driven element 14 has
completely failed.
[0049] With reference to FIG. 11, the power distribution assembly
10 is shown. The power distribution assembly 10 includes the prime
mover 12 and the driven element 14. Additionally, the torque
activated disconnect element 34 is mounted on the shaft 22 and
shown in schematic form. The shaft 22 is rotationally supported by
the first and second bearings 24, 26. Further, a labyrinth first
contact member 20' and a labyrinth first seize ring 32' are shown.
The labyrinth first contact member 20' and labyrinth first seize
ring 32' cooperate to provide enhanced sealing capability for the
driven element 14, while also providing the functionality and
makeup of the first contact member 20 and first seize ring 32 as
described hereinbefore. Further, the labyrinth first contact member
20' and the labyrinth first seize ring 32' are the same as the
previously described first contact member 20 and first seize ring
32, except that the labyrinth first seize ring 32' defines a groove
32a' that circumferentially extends around the labyrinth first
seize ring 32' for receipt of a blade 20a' of the labyrinth first
contact member 20' to define a labyrinth seal.
[0050] The labyrinth first contact member 20' also includes a leg
20b' that connects a main body 20c' of the labyrinth first contact
member 20' and the blade 20a' together. As will be appreciated, all
of the components of the labyrinth first contact member 20' can be
integral. The leg 20b' extends in a direction generally parallel to
the shaft 22 and the main body 20c' is disposed radially outward
from the first seize ring 32. The blade 20a' extends generally
perpendicular to the shaft 22 so as to connect the leg 20b' and the
main body 20c' together. As will also be appreciated, the previous
description relating to the interaction between the first contact
member 20 and first seize ring 32 during normal and non-normal
operation is the same as the interaction between the labyrinth
first contact member 20' and the labyrinth first seize ring 32'. It
is noted that the labyrinth first contact member 20' and the
labyrinth first seize ring 32' provide increased surface area for
contact with one another as opposed to the first contact member 20
and the first seize ring 32, thereby providing enhanced
functionality with regard to seizing capability.
[0051] With reference to FIG. 12, the power distribution assembly
10 is once again shown. The power distribution assembly 10 includes
the prime mover 12 and the driven element 14. Additionally, the
torque activated disconnect element 34 is mounted on the shaft 22
and shown in schematic form. The shaft 22 is rotationally supported
by the first and second bearings 24, 26. Further, the first contact
member 20 and the first seize ring 32 are shown. An oil slinger 30
can be directly attached to the first seize ring 32. As shown in
FIG. 12, the first contact member 20 and the first seize ring 32
can have a same longitudinal width (i.e., left to right dimension
in FIG. 12).
[0052] The oil slinger 30 longitudinally extends from the first
seize ring 32 toward the prime mover 12, thereby resulting in a
longitudinal projection. As illustrated, the oil slinger 30 defines
an outer diameter that is equal to the outer diameter of the first
seize ring 32. The oil slinger 30 cooperates with the first contact
member 20 and the first seize ring 32 to improve the sealing
capability of the power distribution assembly 10. Notably, as shown
by the dashed arrow in FIG. 12, any contaminants located near the
oil slinger 30 are slung radially outward and prevented from
entering the driven element 14.
[0053] With reference to FIG. 13, the power distribution assembly
10 is once again shown. The power distribution assembly 10 includes
the prime mover 12 and the driven element 14. The torque activated
disconnect element 34 is mounted on the shaft 22 and shown in
schematic form. The shaft 22 is rotationally supported by the first
and second bearings 24, 26. Further, the first contact member 20
and the first seize ring 32 are shown.
[0054] The driven element 14 can also include a second seize ring
40. The second seize ring 40 can be in addition to the first seize
ring 32. The second seize ring 40 may also have the same
dimensions, be made of the same material, and operate in the same
manner as the first seize ring 32. For example, the first seize
ring 32 can define an outer diameter that is equal to an outer
diameter that is defined by the second seize ring 40. As
illustrated, the second seize ring 40 is disposed between the
torque activated disconnect element 34 and the second bearing 26.
The second seize ring 40 can also be disposed between the torque
activated disconnect element 34 and the first bearing 24.
[0055] Additionally, the second seize ring 40 can also be disposed
between the torque activated disconnect element 34 and the first
seize ring 32. The second seize ring 40 interacts with a second
contact member 20a. Notably, the second seize ring 40 and second
contact member 20a interaction is the same as the previously
described interaction between the first seize ring 32 and the first
contact member 20.
[0056] It will be appreciated that by having a first seize ring 32
interacting with the first contact member 20 and a second seize
ring 40 interacting with the second contact member 20a, an improved
performance can be noted. Additionally, it will also be appreciated
that contact between the first seize ring 32 and the first contact
member 20 and/or between the second seize ring 40 and the second
contact member 20a will have the same result as if there was merely
contact between the first seize ring 32 and the first contact
member 20.
[0057] The driven element 14 can include an oil inlet 44 that is in
fluid communication with the prime mover 12. The oil inlet 44 can
be located near a top of the driven element 14 and allows for oil
46 to be dispensed onto the components within the driven element 14
for cooling and/or lubrication purposes. The oil 46 then collects
in an oil sump 52. The oil sump 52 can be located near a bottom of
the driven element 14 and is in fluid communication with an oil
outlet 48. Although not explicitly shown in FIG. 13, it will be
understood that the oil outlet 48 is fluidly connected to the prime
mover 12 to return the oil 46 to the prime mover 12.
[0058] It will also be appreciated that other thermally driven
failure mechanisms could disconnect the prime mover 12 and the
driven element 14 from one another. For example, in an oil cooled
machine, if flooding occurred, hot circulating oil would heat
either the first seize ring 32 and/or the second seize ring 40,
thereby causing radial expansion of the first seize ring 32 and/or
the second seize ring 40. This would subsequently result in contact
with the respective first contact member 20 and/or second contact
member 20a. For reference, this radial expansion of the first seize
ring 32 and/or the second seize ring 40 due to thermal overheating
could be caused by a variety of reasons.
[0059] For example, it will be appreciated that non-constant
contact between either the first seize ring 32 and the first
contact member 20 and/or between the second seize ring 40 and the
second contact member 20a could result in pieces of the components
(i.e., the first seize ring 32, the first contact member 20, the
second seize ring 40, and/or the second contact member 20a) being
broken off from and resting near the oil outlet 48. These pieces
would then prevent the oil 46 from leaving the oil sump 52 through
the oil outlet 48. This would then cause a level of the oil 46 to
dramatically rise within the driven element 14, thereby flooding
the driven element 14.
[0060] As noted hereinbefore, post-failure rotation of the shaft
can be especially taxing on an aircraft engine. Further, this
rotation of the internal components of the driven element, in the
post-failure mode, can result in additional damage occurring to the
driven element. As driven element can many times be rebuilt or
repaired after a failure, it is desirable for any additional damage
to the driven element to be minimized. Thus, the present assembly
allows for a rapid shutdown of the driven element 14, thereby
minimizing labor and increased material costs associated with a
more thorough rebuilding/repair of the driven element.
[0061] As is considered apparent, the apparatus described in this
disclosure is a notable improvement over the conventional
arrangements listed above due to its simplicity and robustness. No
complex assemblies, electronics or programming logic is required to
safely manage the bearing failure. Rather, simple parts and
geometry are utilized which translates into lower manufacturing
costs and also lower weight. As this system results in a
substantially lower weight, as compared to a back-up bearing
system, the operating cost for any aircraft that includes this
system is lower.
[0062] A power distribution assembly has been described above with
particularity. Modifications and alterations will occur to those
upon reading and understanding the preceding detailed description.
The invention, however, is not limited to only the embodiments
described above. Instead, the invention is broadly defined by the
appended claims and the equivalents thereof. Moreover, it will be
appreciated that various of the above-disclosed and other features
and functions, or alternatives or varieties thereof, may be
desirably combined into many other different systems or
applications, also that various presently unforeseen or
unanticipated alternatives, modifications, variations, or
improvements, therein may be subsequently made by those skilled in
the art which are also intended to be encompassed by the following
claims.
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